1. Field
Embodiments of the invention relate generally to a semiconductor switch.
2. Background Art
In a radio-frequency circuit section of a cellular phone, a transmitting circuit and a receiving circuit are selectively connected to a common antenna through a switching circuit for radio-frequency signals. A high electron mobility transistor (HEMT) made of a compound semiconductor has been conventionally used as a switching element of the switching circuit for radio-frequency signals. Increasing demands of recent years for lower costs and miniaturization encourage the idea of replacing the HEMT with a metal oxide semiconductor field effect transistor (MOSFET) which is formed on a silicon substrate.
A MOSFET formed on an ordinary silicon substrate, however, has a large parasitic capacitance between the silicon substrate and either the source electrode or the drain electrode. In addition, silicon, which is a semiconductor material, causes a large electric-power loss of radio-frequency signals. One of the techniques to address these problems is to form a switching circuit for radio-frequency signals on a silicon-on-insulator (SOI) substrate (see, for example, JP-A 2005-515657 (Kokai)).
A radio-frequency switch of a MOSFET has to internally generate an appropriate gate potential in order to acquire the radio-frequency characteristics (e.g., the insertion loss, and the on-distortion/off-distortion) required, for example, in a cellular phone.
Such voltage generation circuit, however, requires a large layout area for controlling potential fluctuations at the time of switching at the switching circuit, and for achieving quicker switching responses.